CM3-Home

1-Wire interface

1-Wire is a device communications bus system designed by Dallas Semiconductor Corp. This article explains how to use it on the CM3-HOME-B and CM3-HOME-F boards

What is a 1-wire bus ?

The most popular use of 1-wire bus is to use the Dallas DS18B20 temperature sensors. The image below illustrates how to wire it on the screw terminals available on the CM3-Home board. It is possible to wire more than one sensor.

As depicted on the CM3-HOME schematic, the 1-wire data line is interfaced through a dedicated buffer in order to allow a more robust bus, therefore it doesn't require a pullup.

Configuration

To use the 1-wire sensor port add this lines to config.txt file and reboot:

# Enable the 1-wire bus 
dtoverlay=w1-gpio,gpiopin=16

The sensor wired are automatically detected by the Linux Kernel and a new directory is created on the folder /sys/bus/w1/devices for each of them.

$ ls /sys/bus/w1/devices/
28-000006c423d3

In this case a temperature sensor with id=28-000006c423d3 has been detected. To read the temperature value type:

$ cat /sys/bus/w1/devices/28-000006c423d3/w1_slave 
a4 01 4b 46 7f ff 0c 10 da : crc=da YES
a4 01 4b 46 7f ff 0c 10 da t=26250

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CM3-HOME-B - Home automation carrier board for Raspberry CM3L module

Motherboard designed to provide a reliable Home Automation solution based on Raspberry Pi CM3L industrial module

Out of stock until november 2019

  • Parts to order separately:
  • NOT INCLUDED Raspberry Compute Module 3L (Product # CM3L)
  • NOT INCLUDED Wifi module (Product # WIFI-2) and antenna (Product # AN-WIFI-01)
  • NOT INCLUDED MicroSD (Product # MICROSD8G-E)
  • NOT INCLUDED Case (Product # CM3-HOME-CASE)
| Product description || CM3-Home catalog |

Sergio Tanzilli
System designer and Acme co-founder
Personal email: tanzilli@acmesystems.it
Webpages: https://www.acmesystems.it - http://www.tanzolab.it - http://www.tanzilli.com
Github repositories: https://github.com/tanzilli and https://github.com/acmesystems